The valves have O-rings that could fail after exposure to cold temperatures, allowing natural gas to leak from the fuel tank and pose a fire risk, NHTSA said. The valve model numbers are 8100-11-T1T1, 8100-37-BB, 8100-44-BB, 8100-77-BB, 8100-84-BB, 8100-94-BB, and 8100-97-BB. They were manufactured from July 2011 through December 2013.

Circle Seal will notify the CNG tank manufacturers of the defect.

To resolve the issue, bi-fuel vehicles with the defective valves will receive replacement valves free of charge. Replacement valves will also be installed in affected CNG vehicles either sold in or registered in the following cold-weather states: Alaska, Colorado, Connecticut, Idaho, Iowa, Illinois, Indiana, Massachusetts, Maine, Michigan, Minnesota, Montana, Nebraska, New Hampshire, New York, New Jersey, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Utah, Vermont, Wisconsin and Wyoming.

The replacement valves are expected to become available in the fall of this year. Vehicle owners will receive two recall notifications – one this month and another when parts are available for installation.

An automotive-related sustainability stakeholder group has announced that it appreciates that language within the Trump administration’s proposed rule aimed at rolling back automobile fuel-efficiency targets set by the Obama administration reflects that "natural gas is an important part of the climate change battle."